1. Field of the Invention
The present invention relates to disk drives. More particularly, the present invention relates to actuator arm assemblies, constituent parts thereof and methods of making such actuator arm assemblies.
2. Description of the Prior Art
A typical hard disk drive includes a head disk assembly (“HDA”) and a printed circuit board assembly (“PCBA”). The HDA includes at least one magnetic disk (“disk”), a spindle motor for rotating the disk, and a head stack assembly (“HSA”) that includes a slider with at least one transducer or read/write element for reading and writing data. The HSA is controllably positioned by a servo system in order to read or write information from or to particular tracks on the disk. The typical HSA has three primary portions: (1) an actuator arm assembly that moves in response to the servo control system; (2) a head gimbal assembly (“HGA”) that extends from the actuator arm assembly and biases the slider toward the disk; and (3) a flex cable assembly that provides an electrical interconnect with minimal constraint on movement. Coupled to the actuator arm assembly is a coil portion of a voice coil motor (VCM).
A typical HGA includes a load beam, a gimbal attached to an end of the load beam, and a slider attached to the gimbal. The load beam has a spring function that provides a “gram load” biasing force and a hinge function that permits the slider to follow the surface contour of the spinning disk. The load beam has an actuator end that connects to the actuator arm and a gimbal end that connects to the gimbal that supports the slider and transmits the gram load biasing force to the slider to “load” the slider against the disk. A rapidly spinning disk develops a laminar airflow above its surface that lifts the slider away from the disk in opposition to the gram load biasing force. The slider is said to be “flying” over the disk when in this state.
FIG. 1A shows an exploded view of portions of a conventional actuator arm assembly that includes two stamped actuator arms. FIG. 1B shows the portions of the conventional actuator arm assembly of FIG. 1A, with the collar fitted to the two stamped actuator arms. Considering now FIGS. 1A and 1B collectively, the portions of the conventional actuator arm assembly shown include a first actuator arm 102, a second actuator arm 104 and an actuator assembly collar 106. A chemical polishing step may be carried out to polish the surfaces of the actuator arms and to remove any unwanted artifacts of the stamping process. The collar 106 may then be fitted to both actuator arms 102, 104, which stiffens the resultant actuator arm assembly 100. Part FIG. 1C shows a portion of a conventional actuator arm assembly. The arm assembly shown in FIG. 1C is fitted with the collar 106 and with the coil portion 121 coupled to the arm assembly by means of a plastic overmold 120. Even though the actuator arms 102, 104 are mechanically coupled to one another by the collar 106, and the coil portion 121 is fitted to the arm assembly by means of a plastic overmold 120, the resultant aggregate structure nevertheless still suffers from unwanted resonance modes, which detrimentally affect the performance of the disk drive in which such a conventional actuator arm assembly is utilized.
From the foregoing, it may be appreciated that less costly and higher performing actuator arm assemblies are desirable.